For most people who have efiled in January up to this point (January 26), their return status is still "pending" because the IRS hasn't yet opened for processing. The IRS officially starts processing returns tomorrow on Monday, January 27, and for most people that is when the clock starts. You'll see in this forum that a few people have been "accepted" because each year the IRS pulls a few returns early for testing purposes.
That being said, once the IRS begins processing on Monday they will have a backlog of early-filed returns. So there's no way to know for sure how long it will take to get the accepted/rejected notice. It can be a few hours, or it could be 24-48 hours, or in some cases a little longer. No one knows yet what will happen on Monday when they open.